Coated articles are known in the art for use in window applications such as insulating glass (IG) window units, vehicle windows, monolithic windows, and/or the like. Such window applications may involve soda-lime-silica based glass coated with coatings such as low emissivity (low-E) coatings. Example soda-lime-silica based glasses are described, for example and without limitation, in U.S. Pat. Nos. 5,214,008, 6,927,186, 6,953,759, 7,560,402, 7,601,660, 7,858,545, and 8,669,197, the disclosures of which are hereby entirely incorporated herein by reference. Low-E coatings typically include at least one infrared (IR) reflecting layer(s) sandwiched between at least first and second dielectric layer, for blocking at least some solar radiation from entering buildings, vehicles, and/or the like. Example low-E coatings are disclosed, for example and without limitation, in U.S. Pat. Nos. 6,576,349, 9,212,417, 9,297,197, 7,390,572, 7,153,579, and 9,403,345, the disclosures of which are hereby entirely incorporated herein by reference.
In certain example embodiments of this invention, there is provided a method and/or system utilizing ellipsometry to detect/identify significant corrosion (e.g., sodium carbonate, calcium carbonate, sodium sulfate, and/or sodium nitrate based corrosion, from Stage 1 and/or Stage 2 corrosion) on soda-lime-silica based glass or on other types of glass, so that such significantly corroded glass can be identified and not coated (e.g., with a low-E coating or other type of coating) and/or not used in applications where optical appearance is critical. In certain example embodiments, ellipsometry is utilized to differentiate between corroded glass and non-corroded glass, so that significantly corroded glass can be detected/identified. In certain example embodiments, the method and/or system using ellipsometry to detect and/or identify corrosion on glass may be part of, or used in conjunction with, a sputtering apparatus that sputter-deposits coatings (e.g., low-E coatings, or other types of coatings) on glass.
In an example embodiment of this invention, there is provided a method of making a coated glass sheet, the method comprising: analyzing an uncoated glass sheet via ellipsometry analysis, including directing radiation toward the uncoated glass sheet so as to be reflected by the uncoated glass sheet; determining (e.g., by at least one processor of an ellipsometry or other system) whether or not the uncoated glass sheet has significant corrosion thereon based on the ellipsometry or other analysis; and selectively allowing the uncoated glass sheet to be coated with a low-E coating (or other coating) based at least on whether significant corrosion is determined to be on the uncoated glass sheet.
The determining may comprise determining whether or not the uncoated glass sheet has significant corrosion thereon based at least on a measured delta (Δ) value, wherein the measured delta (Δ) value is based on at least a polarization change between the radiation incident on the uncoated glass sheet and the radiation reflected by the uncoated glass sheet. The determining may comprise determining whether or not the uncoated glass sheet has significant corrosion thereon based at least on whether the measured delta (Δ) value exceeds a predetermined value, so that it is determined that the uncoated glass sheet is not significantly corroded when the measured delta (Δ) value exceeds the predetermined value, and it is determined that the uncoated glass sheet is significantly corroded when the measured delta (Δ) value does not exceed the predetermined value. The measured delta (Δ) value may comprise at least one delta (Δ) value measured for at least one wavelength from about 190-1,000 nm, more preferably from about 290-500 nm. The glass sheet may be a soda-lime-silica based glass sheet, and/or the corrosion may comprise at least one of sodium carbonate, calcium carbonate, sodium sulfate, and sodium nitrate based corrosion.
In certain example embodiments, a processor may be configured to determine whether or not the glass sheet has significant corrosion thereon based at least on at least a plurality of measured delta (Δ) values from the glass sheet, and based at least on whether more than a predetermined number of the plurality of measured delta (Δ) values exceed the predetermined value and/or are less than the predetermined value.
In certain example embodiments, a processor may be configured to determine whether or not the glass sheet has significant corrosion thereon based at least on a plurality of measured delta (Δ) values from the glass sheet and based on a standard deviation of the plurality of measured delta values.
In certain example embodiments, a processor may be configured to determine whether or not the glass sheet has significant corrosion thereon based at least on a plurality of measured delta (Δ) values from the glass sheet and based on differences in values between the plurality of measured delta values (e.g., based on whether the delta values from the sheet are substantially spread out which indicates corrosion, or whether they are all close together indicating a lack of corrosion). This embodiment may or may not be used in connection with any other embodiment described herein.